Shimming - was: Was it something I said?

[Richard Brekne]

Farrell wrote:

> OK, a theoretical problem. If the new "stronger" shim causes the adjacent
> "damaged/crushed/old" soundboard wood to develope cracks along the new shim,
> wouldn't epoxy do the same thing? Certainly the epoxy isn't going to squish
> much. Or do you somehow let thin epoxy soak into the adjacent old board
> material and then put a thickened mixture into the crack. Also, when doing
> an epoxy "shim", is there any reason to rout out the crack? Or do you just
> fill it as is?

I certainly cant give you the technical reasons.. but as I understand it the
expoxy soaks in to the wood to some degree. Also as Del was getting into its a
purely chemical reaction... with no (or almost no) curing related to gases
evaporating out of the glue.  In anycase I have yet to see an epoxy "shim" fail.

As far as routing out... this mostly a cosmetic thing... so whatever looks best
to you.  I have seen fellows who combine the two proceedures actually, tho I
dont know what the success /failure picture is on that. I personally scrape out
with a standard "V" tool just enough to allow for a line of epoxy to run into.
If the crack is already wide enough, then I just tape and glue.

My own preference for looks is a dark colour.  I want it to show.... nicely
lacked it gives a neat effect. But I know many who want the repair to
"disapear"... To each their own.

>
> Terry Farrell
> Piano Tuning & Service
> Tampa, Florida
> mfarrel2@tampabay.rr.com
>
> ----- Original Message -----
> From: "Delwin D Fandrich" <pianobuilders@olynet.com>
> To: <pianotech@ptg.org>
> Sent: Monday, January 08, 2001 10:39 AM
> Subject: Re: Shimming - was: Was it something I said?
>
> >
> > ----- Original Message -----
> > From: "Farrell" <mfarrel2@tampabay.rr.com>
> > To: <pianotech@ptg.org>
> > Sent: January 08, 2001 5:42 AM
> > Subject: Shimming - was: Was it something I said?
> >
> >
> > > Makes sense Del. I fit my shims by adjusting the thickness of them (they
> > are
> > > cut on a small angle as is the slot - trimming the thickness makes them
> > > wider or narrower). Therefore, I start with shims thicker than my board.
> > How
> > > does one get around this using old soundboard stock that is the same
> > > thickness or thinner than the target board? Laminate two thicknesses
> > > together? Are we not then moving toward a shim that is stronger than the
> > > target board?
> > >
> > > Terry Farrell
> > -------------------------------------------------------
> >
> > Don't know, Terry. Laminating them might work. I haven't shimmed a board
> > with either old or new wood since sometime in the very early 70s, having
> > switched to epoxy about that time. Once I did my first epoxy 'shim' I
> never
> > went back -- in spite of the many critics of the day who assured me that
> > they wouldn't work. They did then and they still do today. Of course,
> today
> > we mostly replace boards rather than shim them.
> >
> > Which ever is you elixir of choice, shimming or epoxying, it's good to
> keep
> > in mind that both are strictly cosmetic repairs. Neither does anything
> > acoustical, either good or bad, regardless of the material used or the
> > quality of the work done. Well, ok, a really badly done shim could buzz, I
> > suppose, and that's acoustical.
> >
> > Del
> >
> >

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:Richard.Brekne@grieg.uib.no